Mechanical properties and durability characteristics of polymer- and cement-based repair materials M.M. Al-Zahrani * , M. Maslehuddin, S.U. Al-Dulaijan, M. Ibrahim Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia Abstract Thisstudywasconductedtoevaluatethemechanicalpropertiesanddurabilitycharacteristicsofninepolymer-andcement-based repair mortars. Mechanical properties, such as compressive, tensile and flexural strength, elastic modulus, shrinkage and thermal expansionwerestudied.Thedurabilitycharacteristicsoftherepairmaterialswereevaluatedbymeasuring:(i)chloridepermeability, (ii) electrical resistivity and (iii) carbonation depth. The mechanical properties of the selected repair mortars did not vary very significantlyfromeachother.Theelasticmodulusofthepolymer-basedrepairmortarswaslessthanthatofthecement-basedrepair mortars. This will lead to a reduced drying shrinkage cracking in the former repair mortars compared to the latter. The electrical resistivity of polymer-based repair mortars was more than that of cement-based repair mortars. Such a trend was not noted in the chloride permeability data. The chloride permeability in all the repair materials was very low according to ASTM C 1202 criteria. Enhanced carbonation was noted in some of the polymer-based repair mortars. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Cement- and polymer-based repair materials; Durability characteristics; Mechanical properties 1. Introduction Reduction in the useful service-life of reinforced concrete construction is a major problem confronting the construction industry worldwide. Concrete deterio- ration due to reinforcement corrosion is evident in the mild climatic conditions of the world while in the hot and arid regions this problem is caused due to a combi- nationofenvironmentalconditions,marginalaggregates and inappropriate construction methods. Considerable resources are expended to repair and rehabilitate the deteriorated concrete structures. Repair and rehabilitation of deteriorated concrete structures are essential not only to utilize them for their intended service-life but also to assure the safety and serviceability of the associated components. A good repair improves the function and performance of the structure, restores and increases its strength and stiff- ness, enhances the appearance of the concrete surface, provides water tightness, prevents ingress of the ag- gressive species to the concrete/steel interface, and im- proves its durability. Severalrepairmaterialsaremarketedfortherepairof deteriorating concrete structures. These repair materials are classified into different types, such as cement, epoxy resins, polyester resins, polymer latex and polyvinyl acetate. Cement-based materials and polymer/epoxy resins are the most widely used among the repair ma- terials [1–3]. These materials mostly consist of a con- ventional cement mortar often incorporating special waterproofing admixtures. These admixtures are com- monly impregnated with one or more additives, such as polymer, silica fume, fly ash or other industrial by- products. Polymer modified cement repair materials are used to overcometheproblemsassociatedwiththecement-based repairmaterials,particularlytheneedforalongercuring period. Over the years, many different polymers have been used in a range of applications in the repair and maintenance of buildings and other structures. Such polymer mortars provide the same alkaline passivation protectiontothereinforcingsteel,asdotheconventional cement materials [4,5]. Polymers are usually used as admixtures; they are supplied as milky white dispersions * Corresponding author. Fax: +966-3-860-3996. E-mail address: mesferma@kfupm.edu.sa (M.M. Al-Zahrani). 0958-9465/03/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0958-9465(02)00092-6 Cement & Concrete Composites 25 (2003) 527–537 www.elsevier.com/locate/cemconcomp